Recovery of sulphur



sePt 26, 1933. R. F. BACON ET-L l17,928,406

RECOVERY oF suLPHun Filed Feb. 25, 1930 Patented Sept. 26, 1933 UNITED STATES PATENT OFFICE Bencowitz, New York,

asslgnor to said Bacon N. Y.; said Bencowitz Application February z5, 1930. serial No. 431,135

1o claim. (ci. ca -224)- This invention relates to the recovery of sulphur and has for an object the provision of an improved process for recovering sulphur from heavy metal sulphide ores. More particularly,

5 the invention contemplates theprovision of an improved process for recovering sulphur from materials containing one or more sulphides of iron. The invention further contemplates the provision of an improved process for treating lo heavy metal sulphide ores such, for example, as ore containing sulphides of iron, copper and nickel.

The process of the present invention involves the treatment of ore or other metallurgical raw materials or products containing pyrites or other sulphides of iron, alone or in combination with sulphides of other heavy metals, such, for example, as copper and nickel, with a chlorinating agent such, for example, as chlorine, sulphuryl chloride or sulphur chloride for` the vpurpose of obtaining free sulphur and/or separating iron from the mass of material undergoing treatment. A

In carrying out a process in accordance with the present invention, a quantity of ore or other material to be treated is subjectedto the action of a chlorinating agent under such conditions that ferrous chloride and free sulphur are produced. The operation is so conducted that the 80 sulphur produced is vaporized, leaving a' residue containing the ferrous chloride together with chlorides of other heavy metals, such as copper 1 and nickel, when the sulphides of such` metals are present in the material undergoing treatment. The sulphur produced is condensed and collected as free sulphur. The residue containing ferrous chloride is subjected to the action of chlorine gas to form and'vaporize ferric chloride. 'I'he ferric chloride produced is subjected to the action of superheated steam to produce hydrogen chloride which is subjected to the action of oxygen to produce free chlorine. The chlorine thus produced is returned to the process.

The invention will be better understood from a consideration of the accompanying owsheet and the following` description of the application of the invention to the treatment of ore containing sulphides of iron, copper and nickel with sulphur chloride.

The ore to be treated is subjected tothe action of sulphur chloride under such conditions that ferrous chloride and free sulphur are produced. The operation is so conducted that the sulphur produced is vaporized, leaving a residue containing the `ferrous chloride together with the chlorides of copper and nickel. T he sulphur may be vaporized by means of inert gases introduced with the sulphur chloride or a temperature suiiiciently high to vaporize the sulphur may be maintained and substantially pure sulphur u chloride vapor may be employed.

The ore is preferably introduced in a dry, finely divided condition into the interior of a rotary reaction chamber having ore charging means at one end and discharging means at the u other end. and which is so constructed and operated that the ore is gradually moved from the charging end toward the discharge end. Sulphur chloride is introduced into the reaction chamber at the end opposite to that at which the ore is introduced and the ore and sulphur chloride pass through the reaction chamber in counter-current relationship. The sulphur chloride may be introduced into the reaction chamber in either the liquid state or the gaseous'state. 75 Liquid sulphur chloride will be vaporized immediately after its introduction. The ore is preferably ground to provide particles sulciently small to pass a 100-mesh screen in order that intimate contact of the sulphur chloride with the sulphide vparticles may be obtained.

The process ispreferably so controlled that a temperature of about 450 C. is maintained near the charging end of the reaction chamber, and a temperature of about 300 C to 350 C is maintained near the discharge end of the reaction chamber. The admission of ore and sulphur chloride are preferably so regulated that all of the sulphur liberated is vaporized and all of the sulphur chloride admittedis consumed. lThe sulphur produced is vaporized and separated from the heavy metal chlorides in the hottest portion of the reaction chamber, and the residue containing the heavy metal chlorides is discharged from the reaction chamber at a temperature of about 300 C to 350 C. The vaporized sulphur is co1- lected and condensed. g

The hot residue containing ferrous chloride is subjected to the action of chlorine gas to produce and vaporize ferric chloride. The treat- 100 ment ofthe ferrous chloride-bearing material is preferably conducted in a rotary reaction chamber which is so constructed and arranged that -material charged into one end portion will move progressively toward the other end portion during its rotation. The ferrous chloride-bearing material and the chlorine gas are preferably introduced into opposite ends of the reaction cham: ber and pass through the reaction chambegflii counter-current relationship. The ferrous chlo- 110 ride-bearing material thus passes gradually into regions of increasing chlorine concentrations and a substantially complete removal of iron from the 4 mass is assured.

The hot residue contains nickel chloride and copper chloride in addition lto ferrous chloride and gangue, and it enters the reaction chamber at a temperature of about 300 C. The chlorine employed for treating the ferrous chloride-bearing material comprises, in part at least, chlorine which is recovered in a subsequent step ofthe process from ferric chloride produced during the course of the treatment, and it is contaminated with inert gases which are introduced into the system. The inert gases may be utilized for sweeping the ferrie chloride from the reaction chamber,

- and the reaction chamber may, therefore, be

maintained at a temperature below the bolli ing point of ferrie chloride. Satisfactory results may be obtained if the reaction chamber is maintained at a temperature of about 300 C., but temperatures above 300 C. and preferably above 315 C., the boiling point of ferric chloride, are more desirable, a temperature of about 350 C. being very satisfactory.

A reaction between ferrous chloride and chlorine proceeds according to the following equation:

The chlorides of nickel and copper remain unchanged and do not vaporize to any substantial extent when a temperature between about 300 C. and 350 C. is maintained.

A residue containing the chlorides of copper and nickel and the gangue contained in the original ore is discharged from the reaction chamber and it may be treated in any desired manner to separate and recover the valuable'components.

The vaporized ferrie chloride is collected and condensed to eliminate inert gases. The condensed ferric chloride is vaporized and subjected to the action of water vapor at an elevated temperature in a suitable reaction chamber. The ferric chloride is hydrolyzed and ferric oxide and hydrogen chloride are formed, the reaction proceeding according to the following equation:

In carrying out the hydrolysis of ferric chloride, ferrie chloride vapor and superheated steam are introduced together into the reaction chamber in such a manner that intimate mixing will result. The reaction may be conducted conveniently at a temperature of about 300 C. to 400 C. Good results may be obtained if the reaction chamber is maintained at a temperature of about 350 C.

The ferric oxide will be produced in the form of a nne powder which may be permitted to settle out in the reaction chamber. The gases issuing from the chamber contain hydrogen chlo- The catalytic reaction chamber preferably consists of a tower, or a series of communicating towers packed with porous material having a very large surface per unit of volume such, fo exam-l ple, as pumice, brick, cinders and the like. The packing material should be of such a nature that it will be inert to the reagents and the products of the reaction. The packing material iscovered or impregnated with the catalyst which promotes a reaction between hydrogen chloride and oxygen, and which may consist of one or purpose two towers, or two series of communicating towers, which may be used alternately are preferably provided.

The apparatus is so constructed that the mass of catalyst bearing material may be maintained at a temperature of from 370 to 400 C. The reaction between the hydrogen chloride and the oxygen of the air is exothermic and it may be so controlled as to permit the proper temperature to be maintained. The reaction will proceed at a temperature as low as 205 C., and a temperature as high as 470 C. may be used advantageously. The temperature at which the reaction is conducted will be governed largely by the nature of the catalyst. The temperature employed should be sufficiently low that excessive volatilization of the catalyst is avoided. The reaction involved in this operation does not proceed to completion. The gases issuing from the reaction chamber will consist of a mixture of hydrogen chloride, water vapor and chlorine.

In view of the fact that the reaction does not readily proceed to completion, it may be desirable to retreat the issuing gases by subjecting them to a drying operation to remove the water vapor and subsequently passing them through a second reaction chamber. This procedure may be repeated two or three or more times if desired. In carrying out the reaction between hydrogen chloride and the oxygen of air it is advisable to carefully control the proportions of air and hydrogen'chloride utilized in order to avoid excessive dilution of the resulting chlorine gas and in order to avoid the incorporation of excessive amounts of free oxygen in the resulting chlorine The gases are washed with water to separate the chlorine and hydrogen chloride. The separated chlorine is dried with sulphuric acid, and a portion of the dried gas is utilized for treating the residue containing ferrous chloride.

The remainder of the chlorine is passed through a bath of molten sulphur which has been obtained by condensing a portion of the sulphur vapor recovered during the treatment of the sulphide-bearing material with sulphur chloride. The sulphur bath is maintained at a temperature above the boiling point of sulphur chloride and the sulphur chloride distills off as formed. The sulphur chloride vapor is collected and condensed to eliminate inert gases and the condensed sulphur chloride is vaporized and returned to the process. The reaction between sulphur and chlorine will proceed at a temperature below the boiling point of sulphur chloride, but it is advantageous to conduct the reaction at a tem- .drogen chloride andchlorine is combined with the water used for separating the hydrogen chloride and chlorine and the resulting liquid is heated to recover hydrogen chloride which is returned to the process. The sulphuric acid which vhas been freed from hydrogen chloride is concentrated and again used for drying purposes.

A ,portion of the steam produced in concentrati ing'the vsulphuric acid is utilized for treating the ferric chloride. The first fractions obtained duringthe concentration of the sulphuric acid will contain hydrogenchloride and the use of these fractions in providing superheated steam .for treating the ferric chloride will permit an added recovery of chlorine.

As a result of the treatment of the hydrogen chloride with air, considerable quantities of inert gases. such as nitrogen, are introduced into the system and must be eliminated to avoid excessive dilution. The inert gases will be mixed with the chlorine gas which is recovered, and consequently, they will be returned to the system lduring the treatment of original ore and 1 during the treatment of the ferrous chloridebearing residue. Elimination of these gases is eifected by condensing the ferric chloride and by .condensing the vaporized sulphur.

The process may be conducted continuously.

A source of freshchlorine is provided to com.-

pensate for chlorine losses due to leakage and the production of nickel and copper chlorides. The fresh chlorine may be supplied as chlorine gas, sulphur chloride or hydrogen chloride and the choice will be determined by the relative costs.

The principal reactions involved in the process are exothermic and enough heat is provided that no heat need be supplied from outside sources. Heat generated during the course of the process may be utilized for carrying out the concentration ofthe sulphuric acid, vaporization of ferric chloride and sulphur chloride and other operations in which temperatures must be increased.

We claim:

1. The method of recovering sulphur from material containing iron sulphide which comprises subjecting the material to the action of achlorinating agent under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, subjecting the ferrous chloride to the action `of chlorine to form ferric chloride, subjecting the ferric chloride to the action of water vapor to produce hys; drogen chloride, treating the hydrogen chloride to recover chlorine, and returning the chlorine thus recovered to the process.

a subjecting the material to the action of a chlorlnating agent under such conditions that ferrouslschloride a'nd elemental sulphur are produced `and 'the sulphur is vaporized, subjecting the ferrouschloride to the action of chlorine 'to form ferric chloride, subjecting the ferricy chloride to the action of water vapor to produce hydrogen chloride. subjecting the hydrogen chloride to the action of air vin the presence of a catalyst to recover chlorine, and returning the chlorine thus recovered to the process.

3. The method of recovering sulphur from material containing iron sulphide which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized. subjecting the ferrous chloride to the action of chlorine to form ferric chloride, subjecting the ferric chloride to the action of water vapor to produce hydrogen chloride, treating the hydrogen chloride to recover chlorine, and returning the chlorine thus recovered to the process.

4. The method of recovering sulphur from material containing iron sulphide which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, subjecting the ferrous chloride to the action of chlorine to form ferric chloride, subjecting the ferric chloride to the action of water vapor to produce hydrogen chloride, subjecting the hydrogen chloride to the action of air in the presence of a catalyst to recover chlorine, and returning the chlorine thus recovered to the process. i i

5. The method of recovering sulphur from iron sulphide-bearing material which comprises subjecting the material to the action lof sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, collecting the vaporized sulphur, subjecting the ferrous chloride to the action of chlorine to form ferric chloride, subjecting the ferric chloride to the action of water vapor to form hydrogen chloride, treating the hydrogen chloride to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, and combining the remainder of the recovered chlorine with a portion of the sulphur produced to regenerate sulphur chloride.

6. The method of recovering sulphur from iron sulphide-bearing material which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, collecting the vaporized sulphur, subjecting the ferrous chloride to the action of chlorine to form ferric chloride, subjecting the ferric chloride tothe action of water vapor to form hydrogen chloride, subjecting the hydrogen chloride to the action of air in the presence of a catalyst to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, and combining the remainder of the recovered chlorine with a portion of the sulphur produced to regenerate sulphur ch1o` ride.

'1. The method of treating material containing iron sulphide which" comprises subjecting the material to the action of sulphur chlorideunder such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized. subjecting the ferrous chloride to the action of chlorine to form and vaporize ferric chloride, condensing the ferric chloride to separate inert gases, subjecting the ferric chloride to the action of water vapor to produce hydrogen chloride, treating the hydrogen chloride to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, utilizing the remainder of the recovered chlorine to regenerate sulphur chloride, and utilizing the sulphur chloride thus produced to treat additional iron sulphide-bearing material.

8. The method of treating material containing iron sulphide which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, subjecting the ferrous chloride to .the action of chlorine to form and vaporize ferric chloride, condensing the ferric chloride to separate inert gases, subjecting the ferrie chloride to the action of water vapor to produce hydrogen chloride, subjecting the hydrogen chloride to the action of air in the presence of a catalyst to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, utilizing the remainder of the recovered chlorine to regenerate sulphur chloride, and utilizing the sulphur chloride thus produced to treat additional iron sulphide-bearing material.

9. The method of treating material containing iron sulphide which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are produced and the sulphur is vaporized, subjecting the ferrous chloride to the action of chlorine to form and vaporize ferric chloride, condensing the ferric chloride to separate inert gases, vaporizing the condensed ferric chloride,

subjecting the vaporized ferrie chloride to the action oi.' superheated steam to produce hydrogen chloride, treating the hydrogen chloride to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, utilizing the remainder of the recovered chlorine to regenerate sulphur chloride, and utilizing the sulphur chloride thus produced to treat additional iron sulphide-bearing material.

10. The method of treating material containing iron sulphide which comprises subjecting the material to the action of sulphur chloride under such conditions that ferrous chloride and elemental sulphur are vproduced anthe sulphur is vaporized, subjecting the ferrous chloride to the action of chlorine to-form and vaporize ferric chloride, condensing the ferric chloride to separate inert gases, vaporizing the condensed ferric chloride, subjecting the vaporized ferric chloride to the action of superheated steam to produce hydrogen chloride, subjecting the hydrogen chloride to the action of air in the presence of a catalyst to recover chlorine, utilizing a portion of the chlorine thus recovered to treat the ferrous chloride, utilizing the remainder of the recovered chlorine to regenerate sulphur chloride, and utilizing the sulphur chloride thus produced to treat additional iron sulphide-bearing material.

RAYMOND F. BACON. ISAAC BENCOWITZ. 

